1995A&A...299..857B

The central region of the L1448 molecular outflow has been mapped in the CO J=1-0 line, and in the λ 2.6mm continuum, with angular resolution of 3"x 2.5"(∼4x10^–3pc at the distance of L1448, 300pc). In the mapped area, there are two partially overlapping outflows emerging from two different continuum sources (L1448/IRS3 and L1448-mm). The continuum maps are used to study the nature of the two exciting sources. The strong mm peak around L1448/IRS3 is coincident in position with the VLA cm source L1448N(B), and it likely is the source driving the outflow in the northern region. L1448-mm is at the origin of the main outflow. The spectral energy distributions confirm that both sources (L1448-mm and IRS3) are among the youngest known protostellar candidates ("Class 0" sources) New details on the structure of the L1448-mm outflow are revealed by the CO observations. Weak line emission at extremely-high velocities is detected along the jet which is at the axis of the outflow. Such emission is associated with the molecular bullets detected with single-dish telescopes. The jet is inclined at PA -21deg, and its actual jet speed is in excess of 200km/s. Limb-brightened cavities are detected at low CO velocities. The cavities have a biconical morphology, suggesting that a bipolar nebula is forming. The formation of the cavity is well explained in the frame of models for jet-driven bipolar outflows, where the jet entrains ambient molecular material through the propagation of large bow-shocks which are able to disturb the ambient gas at long transverse distances from the jet axis. A comparison of the CO data with H₂ images at 2.12µm provides further support to this scenario. The blueshifted lobe of the L1448-mm outflow exhibits a continuous bending that can be explained as a result of direct collision of the two outflows in L1448.